Plunger for a plunger-lift pumping system

ABSTRACT

A plunger for a plunger-lift pumping system which includes an elongate cylindrical body having a first end and a second end. A plunger suspension coupling is positioned at the first end of the body. A plurality of annular members are provided having central openings and a first radial dimension. The cylindrical body extends through the central openings of the annular members, such that the annular members overlie the cylindrical body. Spacers are provided for maintaining spacing between the annular members. The spacers have a second radial dimension which is less than the first radial dimension, thereby forming circumferential spaces along the cylindrical body between the annular members. A first retainer stops axial movement of the annular members at the first end of the body. A second retainer stops axial movement of the annular members at the second end of the body.

FIELD OF THE INVENTION

[0001] The present invention relates to a plunger for a plunger-lift pumping system

BACKGROUND OF THE INVENTION

[0002] Plunger-lift pumping systems are used in oil or gas wells which have marginal flow characteristics. The well's own energy is used for lift. Liquids are pushed to the surface by the movement of a free-travelling plunger, travelling from the bottom of the well to surface. Plunger travel is normally provided by formation gas which builds up in the casing annulus below the plunger.

[0003] Plungers in current use consist of a cylindrical bar having a fishneck at one end to facilitate removal of the plunger from the well. Circumferential grooves are machined along the length of the cylindrical bar at spaced intervals to facilitate lift of the plunger.

[0004] SUMMARY OF THE INVENTION

[0005] The present invention relates to a novel construction of plunger.

[0006] According to the present invention there is provided a plunger for a plunger-lift pumping system which includes an elongate cylindrical body having a first end and a second end. A plunger suspension coupling is positioned at the first end of the body. A plurality of annular members are provided having central openings and a first radial dimension. The cylindrical body extends through the central openings of the annular members, such that the annular members overlie the cylindrical body. Spacers are provided for maintaining spacing between the annular members. The spacers have a second radial dimension which is less than the first radial dimension, thereby forming circumferential spaces along the cylindrical body between the annular members. A first retainer stops axial movement of the annular members at the first end of the body. A second retainer stops axial movement of the annular members at the second end of the body.

[0007] The plunger, as described above, has a unique structure which provides a number of advantages that will hereinafter be further described.

[0008] There are various forms that the first retainer can take. Beneficial results have been obtained when the first retainer is integrally formed on the cylindrical body. In the embodiment which will hereinafter be described with reference to the drawings, the first retainer is an annular shoulder. An annular shoulder can readily be machined on to the cylindrical body.

[0009] Similarly, there are various forms that the spacers can take. Beneficial results have been obtained when the spacers are integrally formed with the annular members, as this reduces the number of components required.

[0010] It is preferred that the annular members be in the form of discs. The use of multiple thin discs provides benefits as each space between the discs serves to increase lifting capacity. There will hereafter be described various forms of annular members, some of which are discs and some of which are not. Discs have the benefit of flexibility. The discs can also be made with selected modifications which alter then performance. For example, sealing annular members can be formed by providing a first radial dimension which is slightly greater than the radial dimension of the first retainer and the second retainer. There are various ways of adapting sealing annular members to their intended use. The sealing annular members which will hereinafter be described are flexible and have an “S” shaped peripheral edge. The “S” shaped peripheral edge can move in and out like a spring to adjust to variations in well bore diameter while accommodating lateral flexing caused during axial movement of the cylindrical body. Scraper annular members can, similarly, be formed by providing a first radial dimension which is slightly greater than the radial dimension of the first retainer and the second retainer. The scraper annular members are not as flexible to facilitate their function as scrapers during axial movement of the cylindrical body in a well bore. Where sand is a problem, some of the annular members can have a modified peripheral edge with gaps to allow passage of sand.

[0011] Although the relative dimensions of the annular members and the retainers is not critical, where discs are used they are relatively delicate and there is a danger that the annular disc members will be damaged if left substantially unsupported. It is, therefore, preferred that the first retainer and the second retainer have the same radial dimension and the first radial dimension of the annular members is at least equal to the radial dimension of the first retainer and the second retainer.

[0012] Although beneficial results may be obtained through the use of the plunger, as described above, even more beneficial results may be made when the second retainer is detachable. Having a detachable second retainer permits field removal and replacement of the annular disc members. It will immediately be recognized the advantages provided by the ability to field service the plunger. However, the most distinct advantage of the above described plunger is the ability to “customize” the plunger in the field to suit a particular application. For applications in which a better seal is required, more sealing annular disc members may be used. For applications in which sand is a problem, more annular disc members with sand gaps may be used. For applications in which paraffin wax build up is a problem, more scraper annular disc members may be used.

[0013] The preferred material for making the annular disc members is polymer plastic. Polymer plastic is relatively inexpensive. Polymer plastic can also be selected for desired performance properties such as temperature resistance, chemical resistance, wear resistance, swelling resistance, and flexibility.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings, the drawings are for the purpose of illustration only and are not intended to in any way limit the scope of the invention to the particular embodiment or embodiments shown, wherein:

[0015]FIG. 1 is a perspective view of a plunger for a plunger-lift pumping system constructed in accordance with the teachings of the present invention.

[0016]FIG. 2 is a side elevation view of the plunger illustrated in FIG. 1.

[0017]FIG. 3 is an exploded perspective view of the plunger illustrated in FIG. 1.

[0018]FIG. 4 is a perspective view of a flush annular disc member for use in the plunger illustrated in FIG. 1.

[0019]FIG. 5 is a side elevation view of the flush annular disc member illustrated in FIG. 4.

[0020]FIG. 6 is a side elevation view, in section, of the flush annular disc member illustrated in FIG. 4.

[0021]FIG. 7 is a front elevation view of the flush annular disc member illustrated in FIG. 4.

[0022]FIG. 8 is a perspective view of a scraper annular disc member for use in the plunger illustrated in FIG. 1.

[0023]FIG. 9 is a side elevation view of the scraper annular disc member illustrated in FIG. 8.

[0024]FIG. 10 is a front elevation view of the scraper annular disc member illustrated in FIG. 8.

[0025]FIG. 11 is a perspective view of a sealing annular disc member for use in the plunger illustrated in FIG. 1.

[0026]FIG. 12 is a side elevation view of the sealing annular disc member illustrated in FIG. 11.

[0027]FIG. 13 is a side elevation view, in section, of the sealing annular disc member illustrated in FIG. 11.

[0028]FIG. 14 is a front elevation view of the sealing annular disc member illustrated in FIG. 11.

[0029]FIG. 15 is a perspective view of a sand passage annular disc member for use in the plunger illustrated in FIG. 1.

[0030]FIG. 16 is a side elevation view of the sand passage annular disc member illustrated in FIG. 15.

[0031]FIG. 17 is a front elevation view of the sand passage annular disc member illustrated in FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0032] The preferred embodiment, a plunger for a plunger-lift pumping system generally identified by reference numeral 10, will now be described with reference to FIGS. 1 through 17.

[0033] Structure and Relationship of Parts:

[0034] Referring to FIGS. 1 through 3, plunger 10 has an elongate cylindrical body 12. Body 12 has a first end 14 and a second end 16. A plunger suspension coupling 18 is positioned at first end 14 of body 12. A plurality of polymer plastic annular members 20 overlie body 12. Referring to FIGS. 4 through 7, annular members 20 have central openings 22 and a first radial dimension, indicated by reference numeral 24. Referring to FIG. 3, body 12 extends through central openings 22 of annular members 20. Referring to FIGS. 4 through 7, spacers 26 are integrally formed as part of annular members 20. Spacers 26 maintain spacing between annular members 20. It will be appreciated that spacers 26 could, alternatively, be manufactured as separate elements. Spacers 26 has a second radial dimension, indicated by reference numeral 28, which is less than first radial dimension 24. Referring to FIGS. 1 through 3, this forms circumferential spaces 30 along cylindrical body 12 between annular members 20. It should be noted that the annular members 20 need not take the form illustrated in FIGS. 4 through 7. It is preferred that alternative forms of annular members 20 to adapt plunger 10 to suit different field conditions.

[0035] Referring to FIGS. 1 and 2, a first retainer 32 is spaced from first end 14 of body 12. First retainer 32 serves to stop axial movement of annular members 20 at first end 14 of body 12. Referring to FIG. 3, first retainer 32 is in the form of an integrally formed annular shoulder 34 on body 12.

[0036] Referring to FIGS. 1 and 2, a second retainer 36 is provided for stopping axial movement of annular members 20 at second end 16 of body 12. Referring to FIG. 3, second retainer 36 is detachably secured to second end 16 of body 12 with a threaded engagement. Second end 16 of body 12 has external threads 38 to facilitate the threaded engagement with second retainer 36. The ability to detach second retainer 36 permits field removal and replacement of annular members 20, as will hereinafter be further described. First retainer 32 and second retainer 36 have the same radial dimension, identified by reference numeral 40. First radial dimension 24 of annular members 20 is at least equal to radial dimension 40 of first retainer 32 and second retainer 36.

[0037] As stated above, it is preferred that annular members be selected to suit the requirements of each particular well. Three additional styles of annular member will now be described with reference to FIGS. 8 through 17. These annular members are disc like.

[0038] Referring to FIGS. 8 through 10, there is illustrated a version of annular disc member which will hereinafter be referred to as a scraper annular disc member and generally identified by reference numeral 42. Scraper annular disc member 42 has all of the features previously described with respect to annular disc member 20, including an integral spacer 26. However, scraper annular disc member 42 is made relatively thin to function as a scraper blade. Scraper annular disc member 42 has a first radial dimension, indicated by reference numeral 44, which is slightly greater than radial dimension 40 of first retainer 32 and second retainer 36. Radial dimension 44, along with the blade-like body enable scraper annular disc member 42 to function as a scraper during axial movement of body 12 in a well bore.

[0039] Referring to FIGS. 11 through 14, there is illustrated a version of annular disc member which will hereinafter be referred to as a sealing annular disc member and generally identified by reference numeral 46. Sealing annular disc member 46 has all of the features previously described with respect to annular disc member 20, including an integral spacer 26. In order to be a sealing annular disc member 46, the annular disc member must have a first radial dimension, indicated by reference numeral 48, which is slightly greater than radial dimension 40 of first retainer 32 and second retainer 36. The particular embodiment of sealing annular disc member 46 illustrated is flexible and has an “S” shaped peripheral edge 50. Peripheral edge 50 moves in and out like a spring to adjust to variations in well bore diameter while accommodating lateral flexing caused during axial movement of body 12. Sealing annular disc member 46 is used for enhanced sealing.

[0040] Referring to FIGS. 15 through 17, there is illustrated a version of annular disc member which will hereinafter be referred to as a sand passage annular disc member and generally identified by reference numeral 52. Sand passage annular disc member 52 has all of the features previously described with respect to annular disc member 20, including an integral spacer 26. However, sand passage annular disc member 52 has a peripheral edge 54 with gaps 56 to allow passage of sand.

[0041] It is preferred that all of the annular disc members described above be made from polymer plastic selected based upon performance properties, such as temperature resistance, chemical resistance, wear resistance, swelling resistance and flexibility.

[0042] Operation:

[0043] The use and operation of plunger 10, will now be described with reference to FIGS. 1 through 17. Referring to FIG. 1, plunger 10, as described above, is particularly well suited for field installations. Referring to FIG. 3, the field technician detaches second retainer 36 from threaded engagement with body 12. Referring to FIGS. 4 through 17, the field technician may then place any combination of annular disc members 20, scraper annular disc members 42, sealing annular disc members 46 or, sand passage annular disc members 52. The new annular disc members are installed by extending body 12 through the central opening 22. Axial movement towards the first end 12 is confined by first retainer 32. When the second retainer 36 is re-attached to body 12, axial movement toward second end 14 is confined by second retainer 32. The plunger 10 is now ready for use in the conditions of the particular well. Should there be a change in well conditions, a substitution of annular disc members can occur to adapt plunger 10 to suit new conditions.

[0044] There have been impressive results obtained from initial field tests of plunger 10. Plunger 10 has demonstrated improved lifting capabilities as compared to existing plungers. It is believed that this is due to a labyrinth sealing action of the disc members. This improved lifting capability has lead to an increase in production. At the same time, plunger 10 has proven to have a longer wear life while reducing the rate of wear on tubing.

[0045] In this patent document, the word “comprising” is used in its non-limiting sense to mean that items following the word are included, but items not specifically mentioned are not excluded. A reference to an element by the indefinite article “a” does not exclude the possibility that more than one of the element is present, unless the context clearly requires that there be one and only one of the elements.

[0046] It will be apparent to one skilled in the art that modifications may be made to the illustrated embodiment without departing from the spirit and scope of the invention as hereinafter defined in the claims. 

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
 1. A plunger for a plunger-lift pumping system, comprising: an elongate cylindrical body having a first end and a second end; a plunger suspension coupling at the first end of the body; a plurality of annular members having central openings and a first radial dimension, the cylindrical body extending through the central openings of the annular members, such that the annular members overlie the cylindrical body; spacers maintaining spacing between the annular members, the spacers having a second radial dimension which is less than the first radial dimension, thereby forming circumferential spaces along the cylindrical body between the annular-members; a first retainer stopping axial movement of the annular members at the first end of the body; and a second retainer stopping axial movement of the annular members at the second end of the body.
 2. The plunger as defined in claim 1, wherein the second retainer is detachable, thereby permitting field removal and replacement of the annular members.
 3. The plunger as defined in claim 1, wherein the first retainer is integrally formed on the cylindrical body.
 4. The plunger as defined in claim 3, wherein the first retainer is an annular shoulder.
 5. The plunger as defined in claim 1, wherein the spacers are integrally formed with the annular members.
 6. The plunger as defined in claim 1, wherein the annular members are discs.
 7. The plunger as defined in claim 1, wherein the first retainer and the second retainer have the same radial dimension and the first radial dimension of the annular members is at least equal to the radial dimension of the first retainer and the second retainer.
 8. The plunger as defined in claim 7, wherein at least some of the annular members are sealing annular members which have a first radial dimension which is slightly greater than the radial dimension of the first retainer and the second retainer.
 9. The plunger as defined in claim 8, wherein the sealing annular members are flexible and have an “S” shaped peripheral edge, such that the peripheral edge can move in and out like a spring to adjust to variations in well bore diameter while accommodating lateral flexing caused during axial movement of the cylindrical body.
 10. The plunger as defined in claim 7, wherein at least some of the annular members are scraper annular members which have a first radial dimension which is slightly greater than the radial dimension of the first retainer and the second retainer, such that they function as scrapers during axial movement of the cylindrical body in a well bore.
 11. The plunger as defined in claim 7, wherein at least some of the annular members have a peripheral edge with gaps to allow passage of sand.
 12. The plunger as defined in claim 1, wherein the annular members are made out of polymer plastic.
 13. The plunger as defined in claim 12, wherein the polymer plastic is selected based upon performance properties, the performance properties including at least one of temperature resistance, chemical resistance, wear resistance, swelling resistance, and flexibility.
 14. A plunger for a plunger-lift pumping system, comprising: an elongate cylindrical body having a first end and a second end; a plunger suspension coupling at the first end of the body; a plurality of annular members having central openings and a first radial dimension, the cylindrical body extending through the central openings of the annular members, such that the annular members overlie the cylindrical body; spacers integrally formed with the annular members for maintaining spacing between the annular members, the spacers having a second radial dimension which is less than the first radial dimension, thereby forming circumferential spaces along the cylindrical body between the annular members; a first retainer stopping axial movement of the annular members at the first end of the body, the first retainer being an integrally formed annular shoulder on the cylindrical body; a second retainer stopping axial movement of the annular members at the second end of the body; the first retainer and the second retainer having the same radial dimension and the first radial dimension of the annular members being at least equal to the radial dimension of the first retainer and the second retainer.
 15. The plunger as defined in claim 1, wherein the annular members are discs.
 16. The plunger as defined in claim 14, wherein at least some of the annular members are sealing annular members which have a first radial dimension which is slightly greater than the radial dimension of the first retainer and the second retainer.
 17. The plunger as defined in claim 15, wherein the sealing annular members are flexible and have an “S” shaped peripheral edge, such that the peripheral edge can move in and out like a spring to adjust to variations in well bore diameter while accommodating lateral flexing caused during axial movement of the cylindrical body.
 18. The plunger as defined in claim 14, wherein at least some of the annular members are scraper annular members which have a first radial dimension which is slightly greater than the radial dimension of the first retainer and the second retainer, such that they function as scrapers during axial movement of the cylindrical body in a well bore.
 19. The plunger as defined in claim 14, wherein at least some of the annular members have a peripheral edge with gaps to allow passage of sand.
 20. The plunger as defined in claim 14, wherein the annular members are made out of polymer plastic.
 21. The plunger as defined in claim 20, wherein the polymer plastic is selected based upon performance properties, the performance properties including at least one of temperature resistance, chemical resistance, wear resistance, swelling resistance and flexibility.
 22. A plunger for a plunger-lift pumping system, comprising: an elongate cylindrical body having a first end and a second end; a plunger suspension coupling at the first end of the body; a plurality of polymer plastic annular disc members having central openings and a first radial dimension, the cylindrical body extending through the central openings of the annular disc members, such that the annular members overlie the cylindrical body; spacers integrally formed with the annular disc members for maintaining spacing between the annular disc members, the spacers having a second radial dimension which is less than the first radial dimension, thereby forming circumferential spaces along the cylindrical body between the annular disc members; a first retainer stopping axial movement of the annular disc members at the first end of the body, the first retainer being an integrally formed annular shoulder on the cylindrical body; a second retainer stopping axial movement of the annular disc members at the second end of the body, the second retainer being detachably secured to the second end of the body with a threaded engagement, thereby permitting field removal and replacement of the annular members; the first retainer and the second retainer having the same radial dimension and the first radial dimension of the annular disc members being at least equal to the radial dimension of the first retainer and the second retainer.
 23. The plunger as defined in claim 22, wherein at least some of the annular disc members are sealing annular disc members which have a first radial dimension which is slightly greater than the radial dimension of the first retainer and the second retainer.
 24. The plunger as defined in claim 23, wherein the sealing annular disc members are flexible and have an “S” shaped peripheral edge, such that the peripheral edge can move in and out like a spring to adjust to variations in well bore diameter while accommodating lateral flexing caused during axial movement of the cylindrical body.
 25. The plunger as defined in claim 22, wherein at least some of the annular disc members are scraper annular disc members which have a first radial dimension which is slightly greater than the radial dimension of the first retainer and the second retainer, such that they function as scrapers during axial movement of the cylindrical body in a well bore.
 26. The plunger as defined in claim 22, wherein at least some of the annular disc members have a peripheral edge with gaps to allow passage of sand.
 27. The plunger as defined in claim 22, wherein the polymer plastic is selected based upon performance properties, the performance properties including at least one of temperature resistance, chemical resistance, wear resistance, swelling resistance and flexibility. 